Displacement type compressor

ABSTRACT

A displacement type compressor includes a compressing mechanism section for performing a compression, a motor for driving the compressing mechanism section, and a crankshaft adapted to be driven in rotation by the motor to rotate the compressing mechanism section. The motor includes stator cores and having claw-type magnetic poles formed of a magnetic powder and circumferentially arranged in alternately meshed states, and annular coils and wound in a toric shape around the claw-type magnetic poles. Thus, the displacement type compressor is capable of being at a high speed and has a reduced size.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a displacement type compressor for treating air, carbon dioxide and another compressible gas, which may be used as an HFC refrigerant or a natural refrigerant, and particularly, to a displacement type compressor which is suitably designed to provide a high output, while being small-sized.

2. Description of the Related Art

A displacement type compressor representative of a scroll compressor, a reciprocal compressor and a rotary compressor is widely utilized in a variety of fields not only as a compressor for a refrigerant air conditioner used for domestic, business, in-vehicle applications or the like, but also as an air supply compressor used for a source of air in a factory, for a fuel cell or the like. A high-energy efficiency is required from the viewpoint of prevention of global warming, and it is desired to reduce the size of the compressor for promoting the reduction in cost.

It is conventionally known that in order to reduce the size of the compressor, the axial length of a motor for driving a compressing mechanism section is reduced, or a claw-type pole motor (a claw-type magnetic pole motor) having no coil end portion is used to reduce the entire length of the compressor. This is described, for example, in JP-A-2001-280247.

In the above-described conventional technique, the reduction in size is provided merely by eliminating a coil end portion, and hence, it is not sufficiently considered that the compressor is operated at a high output and at a high speed in a range of larger capacity. For this reason, claw-type magnetic poles must be axially stacked as multiple layers for the purpose of an increase in output, and the increase in output results in the impairment of reduction in size for the original purpose.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a displacement type compressor which is capable of being rotated at a high output and at a high speed and has a high-energy efficiency and which is small-sized. It is another object of the present invention to ensure that the axial length of, particularly, a displacement type compressor is reduced, and the reliability is enhanced.

To achieve the above object, according to the present invention, there is provided a displacement type compressor, comprising a compressing mechanism section adapted to perform a compression, and a motor for driving the compressing mechanism section, wherein the motor comprises a stator core in which claw-type magnetic poles formed of a magnetic powder are circumferentially arranged in alternately meshed states, and annular coils wound in a toric shape around the claw-type magnetic poles.

With the arrangement of the above feature, the motor is constructed using the claw-type magnetic poles formed of the magnetic powder. Therefore, it is possible to provide a displacement type compressor which is capable of being rotated at a higher speed and which has a high-energy efficiency.

The above and other objects, features and advantages of the invention will become apparent from the following description of the preferred embodiment taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing the entire compressor according to one embodiment of the present invention;

FIG. 2 is a sectional view showing a stator core in the embodiment;

FIG. 3 is a plan view showing a claw-type core portion in the embodiment;

FIG. 4 is a sectional view showing the claw-type core portion in the embodiment;

FIG. 5A is a plan view of a rotor in the embodiment;

FIG. 5B is a plan view of other rotor in the embodiment;

FIG. 5C is a plan view of other rotor in the embodiment;

FIG. 6 is a sectional view showing the entire compressor according to another embodiment of the present invention;

FIG. 7 is a sectional view showing the entire compressor according to a further embodiment of the present invention;

FIG. 8 is a view showing the entire compressor according to a yet further embodiment of the present invention; and

FIG. 9 is a sectional view showing the entire compressor according to a yet further embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

A displacement type compressor according to an embodiment of the present invention will now be described with reference to FIGS. 1 to 5.

The displacement type compressor includes a compressing mechanism section 1 using a scroll compressing mechanism which is small-sized and capable of providing a high output, and a drive means contained in a closed container 5 for driving an orbiting scroll 3 in orbiting movement. The compressing mechanism section 1 comprises a fixed scroll 2, the orbiting scroll 3 and a frame 4 as basic elements. The fixed scroll 2 or the frame 4 is fixed to the closed container 5.

The fixed scroll 2 includes a spiral wrap 2 a, a mirror plate 2 b and a discharge bore 2 c, and is fixed to the frame 4 through a bolt. The wrap 2 a is mounted on the mirror plate 2 b to rise vertically. The orbiting scroll 3 has a spiral wrap 3 a, a mirror plate 3 b and a shaft support portion 3 c. The wrap 3 a is mounted on the mirror plate 3 b to rise vertically. A compression chamber 7, in which the fixed scroll 2 and the orbiting scroll 3 are meshed with each other, performs a compressing motion, whereby the volume of the compression chamber 7 is decreased by the orbiting movement of the orbiting scroll 3.

With the orbiting movement of the orbiting scroll 3, a working fluid is drawn via an intake space 9 into the compression chamber 7, and the drawn working fluid is discharged through the discharge bore 2 c into a discharge space 10 via a compression stroke and further discharged from the closed container 5 via a discharge port 11. This causes a space within the closed container 5 to be maintained at a discharge pressure. An over-compression preventing means (not shown) is also mounted in order to prevent an over-compression caused during an operation with a pressure ratio lower than a design pressure ratio. The over-compression preventing means includes a passage permitting the communication between the compression chamber 7 and the discharge space 10, and a valve adapted to open the passage when an over-compression is reached.

The drive means for driving the orbiting scroll 3 in orbiting movement includes a motor 23 comprising a stator 21 using stator cores 21 a, 21 b and 21 c with claw-type core portions formed of a magnetic powder and meshed with each other, and a rotor 22, a crankshaft 24, an Oldham's ring 25 which is a main component for an automatic preventing mechanism for the orbiting scroll 3, the frame 4 and a sub frame 12.

The motor 23 provides a rotating action to the crankshaft 24. The crankshaft 24 includes a main shaft portion 24 a, a sub shaft portion 24 b and an eccentric pin portion 24 c. A shaft support portion 6 disposed on the frame 4 and a shaft support portion 26 disposed on the sub frame 12 provide shaft supports with which the main shaft portion 24 a and the sub shaft portion 24 b of the crankshaft 24 are rotatably engaged, and the eccentric pin portion 24 c of the crankshaft 24 is engaged for movement in a rotationally axial direction and for rotation with the orbiting shaft support portion 3 c disposed on the orbiting scroll 3. The shaft support portions 6 and 26 for the crankshaft are disposed on the side of the compressing mechanism section 1 opposite from the motor and on the side of the motor opposite from the compressing mechanism section, respectively. It should be noted that in addition to a sliding bearing, a rolling bearing adaptable for service conditions and another shaft support member may be used for each of the shaft support portions 3 c, 6 and 26.

The Oldham's ring 25 is disposed in a space defined by the orbiting scroll 3 and the frame 4. One of two sets of perpendicular key portions formed on the Oldham's ring 25 slides in a key groove 27 a which is a receiver for the Oldham's ring 25 and formed in the frame 4, and the remaining one set slides in a key groove 27 b formed in a back of the orbiting scroll wrap 2 a. Thus, the orbiting scroll 3 is orbited, without being rotated about its own axis, in a plane perpendicular to an axial direction which is a direction of rising of the scroll wrap.

To fix the stator 21 within the closed container 5, the stator cores 21 a, 21 b and 21 c are accommodated into a core frame 30, and the core frame 30 is engaged with the fixed scroll 2. If a mating member with which the core frame 30 is engaged is the fixed scroll 2, the engagement can be achieved at a high accuracy, but the core frame 30 may be engaged with a portion of the compressing mechanism section 1, or the closed container 5.

FIG. 2 shows one of the stator cores 21 a, 21 b and 21 c in an enlarged scale, wherein the stator core includes a first claw-type core portion 31 and a second claw-type core portion 32. Annular coils 21 d, 21 e and 21 f are provided within the stator core.

A claw-type magnetic pole 33 is provided in an axially folded state on the claw-type core portion in the form of a magnetic pole surface opposed to the rotor 22. The annular coils 21 d, 21 e and 21 f are wound in a toric shape around the claw-type magnetic poles 33. In the stator core, two claw-type core portions are arranged circumferentially in a state in which the claw-type magnetic poles provided on the claw-type core portions are alternately meshed together.

Further, FIG. 3 is a view showing the arrangement of the second claw-type core portion 32, and FIG. 4 shows a section of the second claw-type core portion 32 taken along a line A-A in FIG. 3. In FIGS. 2 to 4, two claw-type magnetic poles are present per one claw-type core portion and hence, four claw-type magnetic poles are present on one stator core. Thus, the motor 23 acts as a four-magnetic pole motor.

As shown in FIG. 1, in the three stator cores 21 a, 21 b and 21 c has the claw-type poles displaced circumferentially by 120° in each of them, and are driven by a three-phase AC power source. Each of the stator cores 21 a, 21 b and 21 c has the claw-type core portions formed of the magnetic powder and hence, if the distance between the outer periphery of the rotor 22 and the claw-type magnetic pole is reduced, it is feared that the magnetic powder is dropped from each of the claw-type core portions, resulting in a detracted reliability. In order to prevent this, a resinous film is formed on each of the claw-type core portions. A material which may be used for the resinous film includes PPS (polyphenylene sulfide)-based resin which is a thermo plastic engineering plastic having a good heat resistance, and the like.

The rotor 22 is preferred to be one having a magnet disposed on its surface, because of its low price, but may be any other rotor such as a cage-shaped rotor as shown in FIG. 5A, a rotor as shown in FIG. 5B and having a cage-shaped conductor and a magnet and a rotor as shown in FIG. 5C and having a flux barrier (slit), if a magnetic pole engaged with a claw-type magnetic pole can be formed on the rotor. In FIG. 5, each of 40 and 41 designates the case-shaped conductor; 42 designates the magnet; and 43 designates the flux barrier.

The sub frame 12 having the shaft support portion 26 disposed thereon is engaged with the core frame 30. It should be noted that a mating member with which the sub frame 12 is engaged may be the closed container 5. The sub frame 12 is provided with a thrust bearing 13 adapted to receive a load when the crankshaft 24 is moved downwards. When the crankshaft 24 is moved upwards, the load is received by a thrust receiver 18.

To lubricate the shaft support portions 3 c, 6 and 26, an oil supply pump 14 is mounted at a lower portion of the sub frame 12 and rotated by the rotation of the crankshaft 24 to realize the pumping action. More specifically, a lubricating oil accumulated in a lower space in the closed container 5 is sucked by the oil supply pump 14 and supplied to the various portions through an oil supply passage 24 d provided in the crankshaft or the like. The oil supply pump 14 may be a centrifugal pump (not shown) formed on the crankshaft to realize an eccentric rotational motion. The lubricating oil supplied to the shaft support portions 3 c and 6 can be supplied only in an amount required for lubricating the inside of the compression chamber 7 through a circular seal member 18 disposed on the frame 4 and a small oil supply bore 20.

In order to eliminate an eccentric unbalance caused by the rotation of the orbiting scroll 3, the eccentric pin portion 24 c of the crankshaft or the like, balance weights 15 and 16 are disposed on the side of the compressing mechanism section 1 opposite from the motor and between the compressing mechanism section 1 and the motor 23, respectively. The balance weight 16 between the compressing mechanism section 1 and the motor 23 is of a shape smaller than inside diameters of the stator 21 and the stator cores 21 a, 21 b and 21 c and hence, is capable of being passed through an inside diameter portion of the stator 21 through the crankshaft 24.

According to the above-described arrangement, the motor 23 using the stator cores with the claw-type core portions formed of the magnetic powder being meshed with one another can be reduced in axial length because of having no end coil, as is a conventional claw-type magnetic pole motor; and this motor is capable of being rotated at a high speed and has a high-energy efficiency characteristic and a high-output characteristic. Therefore, the axial length of the crankshaft 24 can be also reduced by the reduction in size of the motor 23, and hence, the deformation of the crankshaft 24 can be reduced to suppress the one-sided striking on the shaft support portion, leading to an increase in reliability of the shaft support portion.

In addition, it is possible to provide a reduction in size and an increase in speed of the displacement type compressor, and because the resinous film is applied to each of the claw-type core portions 31 and 32 to prevent the dropping of the powder from the claw-type core portions 31 and 32, it is possible to prevent the biting-in of foreign matters in the compressor, leading to an increase in reliability.

Further, because the claw-type core portions 31 and 32 formed of the magnetic powder are contained in the core frame 30, it is possible to prevent the fracture of the claw-type core portions due to the fitting of the stator core into the closed container, and to eliminate the deformation of the closed container due to the fitting. This means that the components to be engaged with the closed contained can be assembled with a good accuracy.

Furthermore, it is possible to position the shaft support portion 6 provided on the frame 4 and the stator core 21 at a coaxiality of a high accuracy.

Yet further, the core frame 30 can be fixed in an engaged manner to the sub frame 12 provided with the shaft support portion 26 and hence, it is possible to position the shaft support portion 6 provided on the frame 4, the stator 21 and the shaft support potion of the sub frame 12 at a coaxiality of a high accuracy.

Moreover, because the axial length of the displacement type compressor can be reduced, the axial length of the crankshaft 24 can be further reduced; the compressing mechanism section 1 and the motor 23 can be disposed between the two shaft support portions 6 and 26 with which the crankshaft 24 is rotatably engaged, and the balance weights for eliminating the eccentric unbalance can be disposed on the side of the compressing mechanism section 1 opposite from the motor and between the compressing mechanism section 1 and the motor 23, respectively, thereby further reducing the deformation of the crankshaft 24 during operation at a high speed. Thus, it is possible to provide an increase in reliability during operation at the high speed and to reduce a loss of sliding of the bearing due to the deformation of the crankshaft.

Further, the outside diameter of the balance weight disposed between the compressing mechanism section 1 and the motor 23 is smaller than the inside diameters of the stator 21 and the stator cores 21 a, 21 b and 21 c and hence, it is possible to enhance the assemblability and to provide a reduction in size and an increase in speed by use of the scroll compressing mechanism section as the compressing mechanism section 1. The arrangement is such that the crankshaft 24 is mounted to extend through the orbiting scroll 3 and the fixed scroll 2, and the compressing mechanism section is sandwiched between the shaft support portions 6 and 26. Therefore, it is possible to rationalize the offset of the load on the shaft support portions and to reduce the deformation of the crankshaft caused by the remarkable eccentric unbalance during operation at the high speed.

A displacement type compressor according to a second embodiment of the present invention will now be described in detail with reference to FIG. 6. FIG. 6 shows the entire structure of a scroll compressor in the second embodiment. The arrangement of shaft support portions 6 and 50 for a crankshaft, a thrust bearing 13, a thrust bearing support portion 51 and an oil supply way are different from those in the first embodiment.

For the shaft support portions for the crankshaft 24, a shaft support portion 50 is formed on a fixed scroll 2. A sub shaft portion 24 e of the crankshaft is rotatably engaged with the shaft support portion 50, and the deformation of the crankshaft 24 due to the whirling of the rotor 22 is influenced at most to a small extent.

The thrust bearing 13 and a thrust bearing 18 for supporting an axial force of the crankshaft 24 are provided on the thrust bearing support portion 51 and the frame 4, but if thrust bearings are provided at opposite ends of the eccentric pin portion 24 c of the crankshaft, the structure is more simplified. In FIG. 6, the thrust bearing support portion 51 is engaged with the core frame 30 by a bolt.

The oil supply way is a centrifugal oil supply way which is effected by the rotation of the eccentric oil supply passage 24 f within the crankshaft 24. Therefore, it is possible to reduce the number of parts, despite the disposition of the shaft support portion 50.

By virtue of the disposition of the shaft support portion 50 for supporting the sub shaft portion 24 c of the crankshaft 24 on the fixed scroll 2, as described above, it is possible to reduce the number of parts in the entire compressor and to construct the compressor having a simple arrangement, a small size and a high efficiency.

A displacement type compressor according to a third embodiment of the present invention will now be described with reference to FIG. 7. FIG. 7 shows the entire structure of a rotary compressor.

A drive source is a motor 23 which is comprised of a stator 21 comprising stator cores 21 am 21 b and 21 c each constituted of claw-type core portions formed of a magnetic powder and meshed with each other and annular coils 21 d, 21 e and 21 f, and a rotor 22. The stator cores 21 a 21 b and 21 c are contained in a core frame 30.

A compressing mechanism section 101 of the rotary compressor is comprised of a cylinder 102, a first end plate 103 and a second end plate 104 for closing opposite ends of the cylinder 102, a roller 105 disposed in a space surrounded by the cylinder 102, the first end plate 103 and the second end plate 104, and a vane (not shown) having a function of changing the volume of a space defined by the cylinder 102, the first end plate 103, the second end plate 104 and the roller 105 in accordance with the movement of the roller 105. A compressing chamber 106 is a space volume which is defined by the cylinder 102, the first end plate 103, the second end plate 104, the roller 105 and the vane, and which is varied in accordance with the movement of the roller 105. A working fluid is drawn via an intake port 107 into the compressing chamber 106. The working fluid is compressed with the movement of the roller 105 and discharged into a discharge space 110 within a closed container 112 via a discharge bore 108 provided in the second end plate 104 and a discharge valve 109 and further discharged from the closed container 112 via a discharge port 111.

A means for driving the roller 105 includes a motor 23, a crankshaft 120, a first end plate 103 and a sub frame 121. The crankshaft 120 includes a main shaft portion 120 a, a sun shaft portion 120 b and an eccentric pin portion 120 c. A shaft support portion 122 disposed on the first end plate 103 and a shaft support portion 123 disposed on the sub frame 121 provide shaft support portions with which the main shaft portion 120 a and the sub shaft portion 120 b of the crankshaft 120 are rotatably engaged, and the roller 105 is rotatably engaged with the eccentric pin portion 120 c of the crankshaft 120. The shaft support portions 122 and 123 for the crankshaft are disposed on the side of the compressing mechanism section 101 opposite from the motor and on the side of the motor 23 opposite from the compressing mechanism section, respectively. In addition to a sliding bearing which may be used for each of the shaft support portions 122 and 123, a rolling bearing is suitable for the rotation at a high speed and at a high load.

A thrust bearing 130 is disposed on the sub frame 121 and adapted to receive a load when the crankshaft 120 is moved downwards. When the crankshaft 120 is moved upwards, a thrust bearing 131 supports the load.

To lubricate slide contact surfaces of the shaft support portions 122 and 123, the roller 105 and the eccentric pin portion 120 c of the crankshaft, a pumping action is realized by employing both of a centrifugal oil supply action caused by the rotation of an eccentric oil supply passage 120 d within the crankshaft 120 and a differential oil supply action caused by a difference in pressure between the compressing chamber 106 and a discharge space 110 within a closed container 112. More specifically, a lubricating oil 132 accumulated in a lower space in the closed container 112 is sucked by the oil supply pumping action and supplied to various portions through the oil supply passage 120 d provided in the crankshaft. An oil supply pump which may be used includes a trochoid pump or the like as an external oil supply pump which is not shown.

In order to eliminate an eccentric unbalance caused by the rotation of the roller 105, the eccentric pi portion 120 c of the crankshaft or the like, balance weights 133 and 134 are disposed on the side of the compressing mechanism section 101 opposite from the motor and between the compressing mechanism section 1 and the motor 23, respectively. The balance weight 134 between the compressing mechanism section 101 and the motor 23 is of a shape smaller than an inside diameter of the stator 21 and hence, is capable of being passed through an inside diameter portion of the stator 21 through the crankshaft 120.

With the above-described arrangement, the axial length of the motor is short, and the axial length of the displacement type compressor can be further reduced using a core frame structure. Therefore, the axial length of the crankshaft 120 can be further reduced; the compressing mechanism section 101 and the motor 23 can be disposed between the two shaft support portions 122 and 123 with which the crankshaft 24 is rotatably engaged, and the balance weights for eliminating the eccentric unbalance can be disposed on the side of the compressing mechanism section 101 opposite from the motor and between the compressing mechanism section 101 and the motor 23, respectively, thereby further reducing the deformation of the crankshaft 120 during operation at a high speed. Thus, it is possible to provide an increase in reliability during operation at the high speed and to reduce a loss of sliding of the bearing due to the deformation of the crankshaft, leading to an increase in energy efficiency.

In addition, the outside diameter of the balance weight 134 disposed between the compressing mechanism section 101 and the motor 23 can be set to be smaller than the inside diameter of the stator 21, leading to an enhanced assemblability. Therefore, it is possible to rationalize the load on the shaft support portions and to further reduce the deformation of the crankshaft caused by the remarkable eccentric unbalance during operation at the high speed, thereby realizing the rotary compressor capable of being operated at the high speed and having a high-energy efficiency.

A displacement type compressor according to a fourth embodiment of the present invention will now be described in detail with reference to FIG. 8. FIG. 8 shows the entire structure of a rotary compressor.

For a shaft support portion for a crankshaft 120, a shaft support portion 140 is provided on a second end plate 104. A thrust bearing 141 and a thrust bearing 131 for supporting an axial force of the crankshaft 120 are formed on the side of the eccentric pin portion 120 c of the crankshaft 120 closer to the motor and at the first end plate 103, respectively, but both of the thrust bearings may be formed at opposite ends of the eccentric pin portion 120 c of the crankshaft, and in the latter case, it is possible to provide a further simplification.

A displacement type compressor according to a fifth embodiment of the present invention will now be described in detail with reference to FIG. 9. FIG. 9 shows the entire structure of a rotary compressor.

This displacement type compressor has a feature in that a compressing mechanism section 154 is disposed in a lower portion of a closed container 112 and balance weights 150 and 151 are disposed at opposite ends of a rotor 22. The balance weights 150 and 151 need not be engaged directly with the rotor 22, and may be disposed on a crankshaft. A thrust bearing 153 and a thrust bearing 152 for supporting an axial force of the crankshaft 120 are formed at opposite ends of an eccentric pin portion 120 c of the crankshaft 120 for the purpose of the simplification. In place of the provision of the thrust bearing 153, a thrust load can be received on a first end plate itself, and in this case, it is possible to provide a further simplified structure.

As described above, a resinous film can be applied to each of claw-type core portions formed of a magnetic powder formed with an insulating film, thereby preventing the dropping of the powder from the claw-type core portions formed of the magnetic powder and constituting a stator core of a motor, thus ensuring the reliability of the displacement type compressor.

In addition, it is not required that the stator core comprised of the claw-type core portions formed of the magnetic powder is fit directly to a compressor casing and hence, it is possible to eliminate a fitting force applied to the claw-type core portions formed of the magnetic powder and to prevent the fracture of the claw-type core portions formed of the magnetic powder. Further, it is possible to reduce the deformation of the compressor casing due to the fitting and hence, it is possible to assemble parts to be engaged with the compressor casing at a good accuracy.

Further, the motor can be disposed in further proximity to the compressing mechanism section and hence, it is possible to provide a reduction in axial length of the displacement type compressor; to ensure the coaxiality at a high accuracy between the crank shaft support portion provided on the side of the compressing mechanism section opposite from the motor and the stator core; and to reduce the flexure of the crankshaft to reduce the deformation of the crankshaft due to an eccentric unbalance during rotation at a high speed, leading to an increase in reliability.

Furthermore, it is possible to maintain the coaxiality at a high accuracy between the crankshaft support portion provided on the compressing mechanism section, the stator core and the crankshaft support portion provided on the motor. Therefore, the balance weights can be passed through the inside of the stator, leading to an enhancement in assemblability of the compressor.

Yet further, the disposition of the crankshaft support portions on the opposite sides of the compressing mechanism section ensures that an increase in a bearing load due to the reduction in length of the crankshaft is not brought out, and besides, the eccentric unbalance during operation at the high speed can be reduced.

It should be further understood by those skilled in the art that although the foregoing description has been made on embodiments of the invention, the invention is not limited thereto and various changes and modifications may be made without departing from the spirit of the invention and the scope of the appended claims. 

1. A displacement type compressor, comprising a compressing mechanism section adapted to perform a compression, a motor for driving said compressing mechanism section, and a crankshaft adapted to be driven in rotation by said motor to rotate said compressing mechanism section, wherein said motor comprises a stator core in which claw-type magnetic poles formed of a magnetic powder are circumferentially arranged in alternately meshed states, and annular coils wound in a toric shape around said claw-type magnetic poles.
 2. A displacement type compressor according to claim 1, wherein each of said claw-type magnetic poles has a resinous film formed thereon.
 3. A displacement type compressor according to claim 1, wherein said compressing mechanism section comprises a fixed scroll and an orbiting scroll meshed with each other to perform the compression by the orbiting movement of said orbiting scroll.
 4. A displacement type compressor according to claim 1, wherein said stator core is fixed to a toric core frame which is disposed within said displacement type compressor.
 5. A displacement type compressor according to claim 1, wherein said compressing mechanism section and said motor are disposed between two shaft support portions on which said crankshaft is rotatably supported.
 6. A displacement type compressor according to claim 1, further including a balance weight disposed between said compressing mechanism section and said motor and having an outside diameter smaller than an inside diameter of said stator core.
 7. A displacement type compressor according to claim 1, further including a balance weight disposed on the side of said compressing mechanism section opposite from said motor.
 8. A displacement type compressor according to claim 1, wherein said compressing mechanism section comprises a fixed scroll and an orbiting scroll meshed with each other to perform the compression by the orbiting movement of said orbiting scroll, and said crankshaft is passed through said orbiting scroll and said fixed scroll and rotatably supported on portions of said orbiting scroll and said fixed scroll through which said crankshaft is passed.
 9. A displacement type compressor, comprising a compressing mechanism section adapted to perform a compression, a motor for driving said compressing mechanism section, a crankshaft adapted to be driven in rotation by said motor to rotate said compressing mechanism section, and two shaft support portions on which said crankshaft is rotatably supported, wherein said motor comprises a stator core in which claw-type magnetic poles formed of a magnetic powder are circumferentially arranged in alternately meshed states, and annular coils wound in a toric shape around said claw-type magnetic poles, said compressing mechanism section comprises a fixed scroll and an orbiting scroll meshed with each other to perform the compression by the orbiting movement of said orbiting scroll, said compressing mechanism section and said motor are disposed between said shaft support portions, and a balance weight is disposed between said compressing mechanism section and said motor and has an outside diameter smaller than an inside diameter of said stator core. 